The present invention relates to a method for producing coenzyme Q.sub.10.
Recently, coenzyme Q.sub.10 has been interested as a raw material for medicines for curing various diseases such as heart diseases, hypertension, tumor etc. and can be produced by various microorganisms. For example, Journal of Fermentation Technology, 47, p 553 (1969) discloses a method of improving productivity of coenzyme Q by adding as a component of culture medium p-hydroxybenzoic acid (abbreviated POBA) which is a precursor in a biosynthetic pathway of coenzyme Q.sub.10. However, the method has a defect that the produced coenzyme Q is Q.sub.9 and not Q.sub.10. Coenzyme Q.sub.9 is substantially inactive to human body and hence it does not exhibit the aforementioned desired pharmaceutical effects.
Japanese patent application publication No. 20,396/72 describes a method for producing coenzyme Q by cultivating a yeast, genus Candida capable of producing coenzyme Q in a culture medium containing n-alkane and POBA or POBA and acetic acid or its salt. However, production of coenzyme Q.sub.10 is not disclosed and production of Q.sub.9 or Q.sub.7 as disclosed is limited due to the feature of using a yeast, genus Candida and to the fact that POBA has generally such a strong toxic property e.g. bactericidal property to microorganisms that it can be used as a food-preservative so that its addition is restricted to 5 mg/l at the most.
Japanese patent application publication No. 19,034/76 describes a method for producing coenzyme Q.sub.10 by cultivating a microorganism of genus Alcaligenes, Trichosporon or Aureobasidium in a nutrient culture medium. However, the method has deficiencies of necessitating a pretreatment step of steam sterilizing the culture medium and thus necessitating a complicated production process.